The invention relates to intravascular catheters that can be used to control patient temperature.
Intravascular catheters have been introduced for controlling patient temperature. Typically, a coolant such as saline is circulated through an intravascular heat exchange catheter, which is positioned in the patient""s bloodstream, to cool or heat the blood as appropriate for the patient""s condition. The coolant is warmed or cooled by a computer-controlled heat exchanger that is external to the patient and that is in fluid communication with the catheter.
For example, intravascular heat exchange catheters can be used to combat potentially harmful fever in patients suffering from neurological and cardiac conditions such as stroke, subarachnoid hemorrhage, intracerebral hemorrhage, cardiac arrest, and acute myocardial infarction, or to induce therapeutic hypothermia in such patients. Further, such catheters can be used to rewarm patients after, e.g., cardiac surgery or for other reasons. Intravascular catheters afford advantages over external methods of cooling and warming, including more precise temperature control and more convenience on the part of medical personnel.
The following U.S. patents, all of which are incorporated herein by reference, disclose various intravascular catheters/systems/methods: U.S. Pat. Nos. 6,419,643, 6,416,533, 6,409,747, 6,405,080, 6,393,320, 6,368,304, 6,338,727, 6,299,599, 6,290,717, 6,287,326, 6,165,207, 6,149,670, 6,146,411, 6,126,684, 6,306,161, 6,264,679, 6,231,594, 6,149,676, 6,149,673, 6,110,168, 5,989,238, 5,879,329, 5,837,003, 6,383,210, 6,379,378, 6,364,899, 6,325,818, 6,312,452, 6,261,312, 6,254,626, 6,251,130, 6,251,129, 6,245,095, 6,238,428, 6,235,048, 6,231,595, 6,224,624, 6,149,677, 6,096,068, 6,042,559.
Because it is sometimes desirable that a patient""s temperature be changed to a desired value as rapidly as possible, the present invention recognizes the need to provide an intravascular heat exchange that has a relatively large cooling and/or rewarming capacity.
A heat exchange catheter includes a body, a coolant supply lumen in the body, and a coolant return lumen in the body. A heat exchange element communicates with the lumens and is configured for placement within a blood vessel of a patient such that blood can flow past the heat exchange element. Coolant is circulated through the body in a closed loop. In one embodiment, the heat exchange element includes longitudinally-spaced, generally square-shaped links when coolant flows through the catheter.
In a preferred non-limiting embodiment, the heat exchange element includes at least first, second, third, and fourth links in sequence, and coolant flows in a proximal to distal direction through the first and third links and in a distal to proximal direction through the second and fourth links. In an exemplary non-limiting embodiment each link defines a generally straight top defining opposed ends and two generally straight legs extending away from the top. Also, a connector segment may connect a leg of one link with a leg of another link. The links may be transversely oriented, i.e., the top of each link can be generally perpendicular to the axis of the catheter. However, in another non-limiting square link embodiment, the top of each link can be generally parallel to a long axis of the catheter. Thus, the links in this embodiment are longitudinally oriented and can be arranged in two sets. The tops of a first set of links are generally colinear with each other and the tops of a second set of links are generally colinear with each other, with the tops of the first set of links being generally parallel to and spaced from the tops of the second set of links.
In another aspect, the heat exchange element includes plural longitudinally-spaced links when coolant flows through the catheter, with each link being configured to establish a single coolant path that directs coolant through the link in a proximal to distal direction for at least a first part of the path and in a distal to proximal direction for at least a second part of the path. This embodiment can include meshed square links or curved, somewhat serpentine-shaped links in which coolant in the first part of the link flows generally up and proximally, and coolant in the second part of the link flows generally down and distally.
In still another aspect, the heat exchange element includes plural longitudinally-spaced links establishing a Venus flytrap configuration when coolant flows through the catheter.
The details of the present invention, both as to its structure and operation, can best be understood in reference to the accompanying drawings, in which like reference numerals refer to like parts, and in which: